For the purpose of realizing the functions of the human hand on a mechanical system, fundamental understanding of the human hand is necessary through intensive observations of manipulation tasks by humans. As an example of skilled manipulation tasks, we target origami folding. We first analyzed the difficulty of origami manipulation and observed how the human folds the origami. We then designed a robotic mechanism that can make an origami work, the Tadpole, in the same way as the human does based on the observation of the origami folding by the human. Although the appearance of the developed robotic hand is dissimilar to that of the human hand, the robot succeeded in performing the origami task, the Tadpole.